We propose a program of research designed to elucidate the normal and abnormal development of the visual mechanisms subserving form and motion vision in humans. We will make an extensive series of measurements regarding the development of cortical selectivity for size, orientation and motion. We will determine how the emergence of selectivity for these attributes correlates with improvements in form and motion acuity. Selectivity for orientation and spatial frequency will be assessed using masking paradigms adapted for use with the VEP. Spatial selectivity will also be studied using a newly developed VEP version of the Westheimer sensitization paradigm. We will study the development of temporal contrast sensitivity and will use temporal masking to study the development of sustained and transient temporal channels believed to underly the temporal CSF. We will study the development of the contrast discrimination function which is of central importance in relating threshold visual performance to suprathreshold performance. The development of motion mechanisms in normal and strabismic infants will be studied using a combination of VEP measurements and correlative eye-movement recordings. We will test the hypothesis that visual motion processing may be abnormal in infantile esotropia and the corollary hypothesis that immaturity in cortical motion processing may underlie the transient asymmetries observed in monocular OKN responses. We will determine the clinical utility of VEP vernier acuity and motion acuity measures in the assessment of visual function of infants with strabismus and/or amblyopia.